Processing of images is a time consuming and CPU intensive procedure because of the shear volume of data to be processed and complexity of algorithms involved.
For this reason, various methods of reducing both the volume of data and the complexity of the image processing algorithms have been developed.
One of the methods relies on reducing the number of distinct colours used to produce an image, even at the expense of the image quality. Instead of storing and managing every primary colour component of every pixel of the image, the most representative colours are grouped into a limited size array of colour elements, in which each element (a colour) is indexed by its position. Such array of colour elements, representing a positive trade off between the number of colours in the set and the image quality, is customarily referred to as a colour map of the image. This way, the pixels of the image contain not the full colour components but merely their index into the colour map and are often referred to as a pixel map of the image. Thus, an image structurally organized into a colour map and a pixel map is called the colour mapped image.
For many applications, colour mapped images are preferred over other types of images, since they are smaller in size and simpler to process, while maintaining an acceptable perceived visual quality.
However, for some applications, such as transformation of images, best known in the art as scaling, benefits provided by colour mapped images are still insufficient. The need for performing scaling may arise, for example, when the size of a high-quality original image exceeds the display or memory capabilities of a mobile device, particularly when a number of images are streamed in a video sequence. In this case, pixels of the image that do not fit into a smaller display must be dropped, which may result in an unacceptable loss of quality of the image because of the lower resolution and no longer adequate colour map. To minimize the damage caused by scaling, prior art suggests to perform a computationally intensive procedures, such as re-generation of the colour map of the scaled image.
However, prior art seems to overlook many opportunities for further minimization of image processing arising during scaling of colour mapped images.
Correspondingly, it is desirable and advantageous to develop an improved method and system for scaling a colour mapped digital image, which would reduce the computational intensity of image processing.